Being a smaller hospital, we RT here at Shoreline don't have many opportunities to take care of patients with Acute Lung Injuries (ALI) or Acute Respiratory Distress Syndrome (ARDS). However, we do on occasion. When this happens, it pays to be up to date on the best methods of caring for these patients.
After much research, we found that the larger hospital in this area has one of the better ALI or ARDS Ventilator strategies.
The gaol with ALI or ARDS is to ventilate at the lowest pressure possible. And, while our ventilator protocol calls for tidal volumes of 6-10cc/kg IBW, the target tidal volume for these processes is 6 cc/kg IBW.
Since pressures is a major issue with ALI & ARDS, it is critical to monitor ventilating pressures, and often the tidal volume must be adjusted based on the ventilating pressures. And, instead of basing the tidal volume on peak inspiratory pressure (PIP), plateau pressure (p-plat) should be used.
Why is this? PIP is a measurement of pressure while a patient is still inhaling, and it measures flow, secretions, and water in the circuit. Static, however, is a measure of pressure once a patient inhales and relaxes. It is a true measure of compliance.
With this in mind, this is why we use p-plat to determine static compliance, which should be in the ranges of 60-100. When the static compliance is <60,>100, then you know you have increased compliance, as you will see with emphasema.
This in mind, here is an abreviated version of an ALI or ARDS Ventilator Strategy, which is ultimately lung protective ventilation:
A. Ideal VT = 6 ml/kg IBW
B. Oxygenation target:
- PaO2 55-80
- SpO2 88-95%
- If PsO2 greater than 80 or sustained SpO2 greater than 95%, decrease FiO2 by 0.1
- If PaO2
- Physician will order changes in PEEP as indicated.
C. pH Goal: 7.30-7.45
- greater than 7.45: Decrease Rate
- less than 7.30: increase rate
- If rate greater than 35, or CO2 >
D. Plateau Pressure: Dr. to select target pressure
- If greater than 30 & due to VT, decrease VT by 50cc Q1 hour until p-plat >
- If >
E. Patients ventilated this way are usually tachypneic. Respiratory rate alone cannot be used as a measure of discomfort in these patients. Some patients require increased sedation to tolerate lung protection ventilation.
F. A patient can still meet lung protective criteria even while on low FiO2s, so lung compliance should not be a criteria for determining use of this protocol. DO NOT MISS AN OPPORTUNITY TO USE LUNG PROTECTIVE VENTILATION BECAUSE THE PATIENT'S LUNG INJURY DOESN'T LOOK THAT BAD.
G. Pt's on lung protective ventilation often are hypercapneic and acidemic. So do not treat abnormal CO2 or pH unless there are advers cardiac effects. Tolerate pH as low as 7.15 and consider the use of Bicarbonate, if necessary, to treat more severe levels of acidosis in order to allow for lung protective ventilation.
H. FiO2 should be maintained as low as possible, and a PEEP study should be completed if ordered by physician (see how to do a PEEP Study post tomorrow).
I. FiO2 can have consequences to the patients lungs, and therefore should be lowered to 60% before decreasing PEEP, so long as there are no complications to high PEEP develop.
Keep in mind I wrote this post not because we do this often at Shoreline, but because when we do have to take care of an ARDS or ALI patient, I am up to date on the latest stategies for taking care of these patients.
For more information, check out ARDS.net.